1. The different designs that have been suggested for the active control of helicopter blades may be classified in two categories, according to their philosophy. In the first group, the time-dependent pitch control is introduced in the nonrotating frame through the helicopter swashplate. This approach is known as higher-harmonic control (HHC). In the second group each blade is individually controlled in the rotating frame. This type of control is called individual blade control (IBC). The HHC has been more amply investigated 2-14 Promising results were obtained, although some limitations were recognized to exit.
2. The aim of the present work is to perform a feasibility study, in which the evaluation of the order of magnitude of the parameters involved are of more interest than the determination of their actual values. A linear mathematical model of a single rotating blade including only the flatwise bending and torsion degrees of freedom was developed. The aeroelastic dimensionless equations are cast in the state-vector form, according to the Hellinger-Reissner-Washizu formulation (Eq. 4a-4f). The dimensionless quantities are defined in Table
3. Equations 4-9 need to be integrated in the independent space variable, r. In this paper, the integrating-matrix method is employed. Integrating matrices have already proved to be an efficient way of systematically integrating systems of ordinary differential equations and formulating eigenvalue